Coloured turquoise on the Tube map, it is by far the shortest line on the Underground network at 2.37 km (1.47 miles),[2] with an end-to-end journey lasting just four minutes. In absolute terms, it is the least-used Tube line, carrying just over 15 million passengers annually. However, in terms of the average number of journeys per mile it is the second-most intensively-used line behind the Victoria line.[4]

The line was built by the Waterloo & City Railway Company and was opened in 1898 (at the time, Bank station was named "City").[5] When it opened it was the second electric underground railway in London, following the City and South London Railway (now part of the Northern line). For much of its existence, it was owned and operated by the London and South Western Railway (later the Southern Railway), before it was nationalised into British Rail. Operations were transferred to London Underground in 1994 following a major refurbishment and replacement of rolling stock.

Contents

The London and South Western Railway (LSWR) reached Waterloo Bridge in 1848, serving routes from Southampton and Richmond. (The name of the terminal station was later changed to Waterloo, and this name is used in the remainder of this article.)

The location was some distance short of the principal commercial area of the City of London, and as regular business travel developed the inconvenience of the location became an issue. The LSWR had hoped to build a line eastwards to near London Bridge but the slump following the railway mania, and the high cost of building through the area, led to abandonment of the idea. When the South Eastern Railway built its extension from London Bridge to Charing Cross, a connecting railway line from it to Waterloo was built; but friction and competitive hostility between the companies frustrated beneficial use of the connection and it fell into disuse at the end of 1867.

A Waterloo Junction station (now called Waterloo East) was built on the Charing Cross line and opened in January 1869, but through ticketing was refused and the onward connection remained frustratingly unsatisfactory.[6]

A Waterloo and Whitehall Railway was promoted in 1864, to construct a tube railway from Great Scotland Yard to Waterloo. It was to use air pressure to propel the vehicles northwards, and exhaust air to draw them southwards, using a pressure differential of 2½ oz per sq in (about 11 mbar). The trains themselves would be the pistons. The company capital was to be £100,000. It was suggested that there could be a branch to where the Embankment station is now located: it is not clear how a junction would be managed in a pneumatic railway. There were to be three vehicles, one loading at each terminal and one in motion in the tube, so they must have been intended to pass at the terminals. There were to be three classes of accommodation in the coaches.

Work started on 25 October 1865, but less than a year later it was obvious that the capital was grossly inadequate. Authority for extension of time and raising more capital was obtained, but by then few investors had any confidence that their investment would pay. In 1868 a further extension was granted, but little further work was done, and nearly all the money had gone.

In 1881 an independent Waterloo and City Railway was promoted, to build a surface line to Queen Street. The cost was formidable at £2.3 million, and the proposal soon collapsed.[6]

In 1891 the Corporation of the City of London made a statistical survey which it published ancillary to the National Census taken in that year. 37,694 persons lived in the City, but the daytime occupation was 310,384. In fact on 4 May 1891 1,186,094 entries to the City were made, i.e., many people entered more than once. Separate statistical information is that about 50,000 persons arrived at Waterloo daily, of whom about 12,000 proceeded to the City by some means.

In November 1891 a bill was deposited to build an underground electric railway from Waterloo to the Mansion House in the City; the capital was to be £500,000; the proposal was supported by the LSWR but was independent. Three other "tube" railways were proposed in the same Parliamentary session, the traditional cut-and-cover method being seen as impractical, as was an elevated railway on viaduct. Electric urban railways had been introduced in Germany in 1891 and in the United States of America, and were in daily, widespread use; but in the United Kingdom, only one example was in existence, the City and South London Railway.

The progress of the bill through Parliament was slow, partly because of the novelty of considering tube railway schemes; there were several petitions from the authorities responsible for public works in the city. The London County Council tried to insist that the tubes should be made large enough to carry ordinary trains, and that all trains arriving at Waterloo should continue through them to the City. This idea would have required a new subterranean terminal station at the Bank of at least equal size to Waterloo itself.

Numerous petitions against the bill, or requiring additional protections to be included in it, were presented, but eventually on 27 July 1893 the Waterloo & City Railway Act obtained Royal Assent.[6][7]

In March 1894 the new company issued its prospectus, and the subscription list closed on 21 April; 54,000 shares at £10 each were offered and there was a slight over-subscription. A dividend of 3% per annum payable out of capital was promised during the construction phase.[6]

Tenders were acquired for the main tunnel work, and a contract was awarded to John Mowlem & Co Ltd for the sum of £229,064[6] (equivalent to £25,620,000 in 2018).[8] The consulting engineers were W R Galbraith (of the LSWR) and J H Greathead, developer of the tunnelling shield. The resident engineer was H H Dalrymple-Hay. Mowlems' engineer in charge was William Rowell.[9]

Mowlem started work on 18 June 1894, first building staging in the river about 500 feet (150 m) west of Blackfriars Bridge. Piles were driven for a cofferdam and two vertical shafts of 16 feet (4.9 m) internal diameter were constructed as headings for the tunnel drive. The average depth of the tunnels is about 45 feet (14 m), with its deepest points at the River Thames, at 63 feet (19 m) underground.

Driving the running tunnels started in November 1894, using the Greathead system of shield excavation, cast iron segment lining, compressed air working, and compressed air grouting behind the tunnel lining. 20 men worked in each heading.[10]

Removal of spoil in tunnelling the Waterloo & City Railway

The excavated material was removed from the staging near Blackfriars Bridge; it was conveyed to there from the shields by a narrow gauge railway using electric locomotives supplied by the Siemens Company. Two were in use and a third was on order at August 1895. They operated on 18-inch (460 mm) gauge track with a twin overhead trolley wire (i.e., not using the track for current return) at 200 V DC.[10]

The station works at Waterloo were constructed by Perry and Co. The station tracks run in separate but adjacent arches supporting the main line station, which run transversely to the main line track. The arch piers needed to be underpinned to about 8 feet (2.4 m) lower than the original foundations.[6]

The route starts from a point halfway between Lower Marsh and Aubyn Street; leaving towards the north west, the line turns in a 339-foot (103 m) curve towards the north east. The curve is constructed by cut-and-cover, and the twin tubes start immediately after it, under Stamford Street, turning north-north-east to pass under the River Thames, converging with Blackfriars Bridge on the north bank. The line turns east there, under Queen Victoria Street, to the station adjacent to the Mansion House, running for part of the way under the District line. The sharpest curves other than those at Waterloo are 603-foot (184 m) radius.

The northbound line falls at 1 in 30 for 900 feet (270 m) from Waterloo; then the line falls at 1 in 120 and then 1 in 800 to the shaft in the river. The westbound line (considered in reverse to the direction of running) falls at only 1 in 60, and then 1 in 550 to the shaft. From there they run together, level for 100 feet (30 m) and then climbing at 1 in 800 for 1,300 feet (400 m), and then 1 in 88 to the terminus.

The tunnels are 12-foot-13⁄4-inch (3.702 m) internal diameter, except for the 603-foot (184 m) curves, where they are 12 feet 9 inches (3.89 m). Each 20-inch (510 mm) long section of tunnel wall was formed with a cast iron ring, made from seven segments and a key piece at the top. 1-inch (25 mm) bolts connect all the segments. Between each section there was a creosoted timber strip 3⁄8-to-1⁄2-inch (9.5 to 12.7 mm) thick, and varying the thickness of this enabled the forward course of the tube to be varied, except in the sharpest curves where the segments were cast to form the curve. There are seven cross-passages between the twin tubes.

Under the Thames the top of the tube is 23 feet (7.0 m) below the bed of the river. The total length of the line is 1 mile 1,012 yards (2,535 m).[9]

The air lock used during compressed air working

The underground station at Waterloo was located within the existing transverse arches of the main line station, with the arrival and departure platforms in separate arches, and a staircase access. Siding accommodation and a reversing siding were provided beyond the platforms: after disembarkation of passengers, an arriving train would continue forward to the reversing sidings, and then return to the departure platform. An additional lay-by siding was provided later.[11]

At the new City station there were two platforms and either could be used by an arriving train, reversing in the platform. The track connections at the approach were a double slip, not a scissors, so a train could not leave while another was arriving.[12] The left hand platform line was extended by a train length and trains could be stabled in the extension.[6] A large diameter Greathead shield was used to bore the section of tunnel where the track connections would be installed.[13]

The tube section for the platform lines at the City station were 23 feet (7.0 m) in diameter, the largest in the world at the time.[6]

In late 1897 contracts were let for the signalling equipment; the electric interlocking was to be carried out by W R Sykes, who had a call-off contract with the LSWR; a supplement to their standard prices for the tunnel work was agreed.

There were signalboxes at Waterloo at the south end of the northbound platform, and at south end of the northbound platform at City. There were conventional semaphore signals in the open south of Waterloo station, but all other signals were electric lights only. Sykes' lock-and-block system was used with depression-type treadles. Although there was only one signal section, advance starting signals were provided. The platform starting signals at Waterloo and at City had a lower arm, a "shunt-by signal" which when lowered indicated that the line was clear only to the advance starting signal. The main starting signal when lowered indicated that the line was clear to City.

An electrical traction current interrupt system was installed; a short length of contact bar was provided at each signal, connected to earth when the signal was at danger, and otherwise isolated. A "slipper" contact was fitted on the trains, and if it contacted the contact bar when it was earthed, the traction current was tripped.[6]

On 4 January 1897 a contract was signed with Siemens and Co for the electrical generating and distribution equipment, and the electrical train equipment, for £55,913. Although a German firm, Siemens had a large presence in the UK at the time. There were three lower tenders.

There were five boilers working at 180 psi (1,200 kPa) driving five (later six) high speed steam engines developing 360 hp (270 kW) directly coupled to dynamos. The two-pole compound-wound dynamos delivered 500 V at no load and 530 V under full load; this gave 225 kW (302 hp) at 350 RPM. Special attention was given to the closeness of the governing to ensure a stable supply voltage. The station lighting circuits were fed from the main switchboard and specially led to maintain lighting supply in the event of a traction current disruption. Station lighting used four lamps in series, with return current via the running rails. (Gas lighting was provided as a back-up.)

There was a short high-level siding within the Waterloo yard area; coal to fuel the boilers was brought in by ordinary LSWR wagons lowered to the running line by the carriage lift; the wagons were drawn through the northbound platform by an electric shunting locomotive, and another lift elevated them to the siding. Boiler ash was disposed of correspondingly.[6]

The City station was not originally called Bank. The Central London Railway (CLR, which became the central section of what is now the Central line) obtained an Act of Parliament in 1891 varying their previously-intended route, to take them to the area of the present-day Bank station. The act required them to construct a central station and booking office and public subways connecting the surrounding streets.[6][7] The subways were to be regarded as public, although maintained by the CLR. Any other railway intending to have a station nearby was entitled to connect to the CLR station by subways. This obviously referred to the Waterloo & City line, and was designed to create a single station frontage in the congested street area. The CLR completed its construction after the W&CR but was obliged to finish the facilities necessary for the earlier opening of the W&CR. The City and South London Railway (CSLR) also operated from the station.

Gillham says, "Right from the start the joint station and circular subway area was always known as the 'City station' by the W&C but as the 'Bank station' by the CLR and the CSLR."[14]

The W&CR station was located some considerable distance from the area near street level, and this later led to persistent complaints as it required passengers to climb a steep and lengthy gradient to reach the exit.

View of the Windsor side of Waterloo in 1979, with a Class 487 car in the background waiting to be returned to the Waterloo & City line after maintenance

The ordinary LSWR permanent way was used, with 87-pound-per-yard (43 kg/m) rails, but in the tubes longitudinal timbers were used instead of cross-sleepers. The sharp curves had check rails. Cross-bonds paralleling the running rails electrically were provided every 100 feet (30 m) and between tracks at the cross passages. The track gauge was the standard 4 feet 81⁄2 inches (1,435 mm).

The conductor rail was a steel inverted channel placed centrally, with its upper surface at the same level as the upper surface of the running rails. At pointwork a hardwood ramp was provided to raise the collector shoes 11⁄2 inches (38 mm) above running rail level.

Part of Siemens' work under the supply of electrical equipment including a shunting locomotive; this was a four-wheel electric locomotive with a cab at one end only, It had two 60 hp (45 kW) traction motors and was delivered in 1898. its main duty was the delivery of the generator station coal. Like the passenger vehicles, its brake system had air reservoirs charged from a static supply at Waterloo. It remained on the system until 1969, when it was transferred to the National Railway Museum at York.

In 1901 a second, more powerful shunting locomotive was acquired. Designed by the LSWR Chief Mechanical Engineer, Dugald Drummond it had two four wheel bogies and was intended for the rescue of failed passenger trains in the tunnel. In 1915 it was removed from the tunnel and put to work shunting coal wagons at Durnsford Road power station, having had its shoe collectors altered for the surface traction supply system.

As the line had no connection to any other line, nor any ground level section, it was necessary to provide a hoist to bring the passenger cars to the line, and to get them out for heavy maintenance. This was provided to the west of the Windsor side of Waterloo main line station, and was known as the Armstrong lift, after the manufacturer, Sir W G Armstrong Whitworth & Co Ltd, who was paid £3,560. It was operated by water power; at the time of construction hydraulic power was commonly used in urban areas, supplied by utility companies, to operate hoists and lifts. The lift was to be capable of lifting 30 short tons (27 t). It was completed in April 1898. There was a smaller 25-short-ton (23 t) hoist within the low-level siding area at Waterloo for the boiler fuel wagons; this had a smaller travel and was installed by John Abbot & Co for £595.[6]

To this day, rolling stock exchanges require the use of road vehicles. Before the construction of Waterloo International terminal in 1990, the vehicles were hoisted individually by the Armstrong Lift outside the north wall of Waterloo main line station. The procedure is now carried out using a road-mounted crane in a shaft adjacent to the depot, south of Waterloo main line station on Spur Road. This is only necessary for major maintenance work that requires lifting of the car body, as the Waterloo depot is fully equipped for routine maintenance work. The remaining stub of the siding tunnel that led to the Armstrong Lift can still be seen on the left-hand side of the train shortly after leaving Waterloo for Bank, but the lift itself was buried (along with the entire Western sidings) in 1992 as part of the construction of Waterloo International station, the terminal for Eurostar trains.

After everything was ready, and the Board of Trade inspecting officer passed the line as fit, Prince George, Duke of Cambridge formally opened the line on 11 July 1898. About 400 persons travelled from Waterloo to the City station and immediately back to Waterloo.

Arrangements had been made for the LSWR to work the line, but not everything was in place for immediate opening: there was a delay of four weeks.

The Waterloo & City Railway opened to the public at 8 a.m. on Monday 8 August 1898, with a train leaving each terminal simultaneously at that time. The fares were 2d one class only, payable at a turnstile, but returns and season tickets, and add-ons to surface tickets were available. From 1900 the turnstiles were done away with and conductors travelled on the trains, carrying Bell Punch ticket machines. The daily average receipts in January 1899 were £86,[11] and with steadily rising passenger usage and income the Company was able to pay a 3% dividend out of income following the annual general meeting of February 1902.[6] Sunday services were not considered at this period, and in 1906 it was stated that "it would cost £20 each Sunday to run the trains, and they would not get that back in receipts."[15]

Very soon after operation, it was realised that the line was running to capacity at the business peaks, then referred to as the rush, and very lightly used for the remainder of the day. Accordingly, in the spring of 1899 an order was placed with Dick, Kerr & Co. for five new motor cars for single operation. The driving cabs were half width; the traction motors, two per car, were 75 hp (56 kW) nose suspended with single reduction gear. As with the earlier cars, the air brake reservoir was charged from static equipment at Waterloo. Five of these single cars were delivered in February 1900 and entered service in the spring. From that time they alone worked the off-peak service, and the original vehicles only worked the peak services.

The line had been worked by the LSWR from the outset, and in 1906 the LSWR made overtures to the W&CR concerning an outright absorption. It was suggested at an Extraordinary General Meeting of the W&CR that increasing competition motivated the LSWR. An enabling Act was passed on 20 July 1906 and shareholders' approval being obtained, the transfer took place on 1 January 1907, with the shareholders receiving LSWR shares, and the W&CR ceased to exist.[6]

In 1915 the LSWR started electrifying its suburban routes, and for the purpose it built a large generating station at Wimbledon, Durnsford Road. The power for train operation on the Waterloo & City line was supplied from this from December 1915, and the original W&CR generating plant now served only ancillary purposes in the line, but also heating and lighting of the main LSWR Waterloo offices. The traction voltage on the W&CR was altered to 600 V (from the original 530 V[16][17][better source needed]).

In 1921 it had been considered desirable to augment train lengths at the busy periods, and four new trailer coaches to the original specification were built at Eastleigh; 24 five-car trains were run per hour at the busiest times.[6]

By the Railways Act 1921, the main line railway companies of Great Britain were grouped into four companies, effective at the beginning of 1923. The LSWR was now part of the Southern Railway. Due to the Waterloo & City's status as part of one of the "Big Four" railway companies, it was not taken over by the London Passenger Transport Board (LPTB) at the latter's formation in 1933, making the W&C the only tube railway in London not to fall under the control of the LPTB. Despite this anomaly, the line was included on most versions of the Underground map produced by the LPTB and its successors up until the line's absorption into the London Underground network in 1994.

In 1934 the LPTB, which now operated most of the London Underground system, proposed that the Waterloo & City should have a new intermediate station at Blackfriars, connecting with the District line station there. They further proposed that the Waterloo & City line should be extended to Liverpool Street station and Shoreditch, the trains there continuing over the East London Railway to New Cross and New Cross Gate. It is not clear whether the scheme had been costed, but nothing came of it.[18]

On 13 April 1948 a serious accident took place at the Waterloo Armstrong Lift; coal was still taken down to the original generating station which powered station offices at Waterloo. A shunt of wagons was being propelled on to the lift at the upper level; four pawls were supposed to be engaged to provide partial support to the lift table, but it appears that some had not engaged. The table tilted, drawing the wagons and M7 locomotive number 672 on to the table; the table and the entire shunt including the locomotive fell down the shaft. The locomotive and wagons were cut up in situ. There is no information as to the fate of the locomotive driver.

When the line was built, the platforms at the Bank (then known as City) were located a considerable distance from the surface exits, and a long sloping tunnel had to be negotiated on foot. This led to constant complaints and from 1929 there were many proposals to improve the arrangements, as passenger numbers increased, adding congestion to the physical exertion. The proposals had variously included new escalators, direct connection to adjacent Central London Railway (later Central line) platforms, and new, closer, tunnelled exits.

In the 1950s a Speedwalk system of people mover consisting of a continuous rubber belt system, was implemented in certain American cities. After considerable delay considering this and alternatives, British Railways let a contract on 4 July 1957 for the civil engineering works in driving a new sloping access tunnel, in which a pair of travolators (at the time often written Trav-O-Lator) would be installed by Waygood Otis. Otis did not, at this stage, get a contract.

However, as work was getting under way, the Government imposed heavy cuts in capital expenditure on the railways, and after considerable deliberation, it was decided once again to defer alleviation of the problem; no financial benefit was anticipated from the scheme, whereas competing schemes would significantly reduce operational costs. The consulting engineers were directed to suspend work on 11 December 1957, although some enabling work, particularly a sewer diversion, proceeded.

The financial restrictions were not long-lasting, and on 10 July 1958 it was announced that the work would resume. It progressed without further major difficulties and a formal opening by the Lord Mayor of London took place on 27 September 1960, coming into public use immediately. There were two parallel travolators, each with a moving surface having 488 platform sections each 40 by 16 inches (1,020 mm × 410 mm); the whole length is 302 feet (92 m) on an inclination of 1 in 7. There was a moving handrail. In the morning peak both travolators would operate upwards, with arriving passengers being required to walk down the original ramps; at other times one travolator operated in each direction. The original OtisTrav-O-Lators have since been replaced by CNIM machines.

In association with the work, some improvements were made to the station environment at the Waterloo station, and a 2½ minute frequency was implemented in the peaks; this involved some minor signalling changes, reversion to alternating platform use at Bank, and the use of turnover drivers and guards (where the arriving driver and guard are replaced by staff waiting at the appropriate place for the change of direction, sometimes referred to as "stepping up"). A Rear Cab Clear plunger is provided at Bank so that the arriving driver can confirm that he is clear of the cab and the "step-back" driver can depart when the signal clears.

On 1 April 1994 the line was transferred to London Underground Ltd.[5] At the time, staff were given the option of transferring with the line or remaining in British Rail employment, and all except one chose the latter. The drivers are currently based at Leytonstone.[citation needed]

From 15 April 1996 the line worked to a new timetable, with three trains departing in each ten minutes during the morning peak.[citation needed]

Up to the time of closure for refurbishment the Class 482 trains carried the original blue British Rail Network SouthEast livery that they had when they were introduced, despite having been part of London Underground for a number of years.[6]

In January 2003, the Waterloo & City was closed for over three weeks for safety checks after a major derailment on the Central line, which required all 1992 tube stock trains to be modified. That same year, responsibility for the line's maintenance was given to the Metronet consortium under the terms of a public–private partnership arrangement.[citation needed]

By 6 January 1898 a skeleton carriage could be run through the tunnels to verify clearances and the first fully assembled train of four carriages was run from Eastleigh to Waterloo on 4 March 1898. The lift for lowering rolling stock to the tunnel level, and some electrical work, were not ready, but on 4 June 1898 a successful trial run was made.

The motor coaches were 47 feet 1 inch (14.35 m) overall length, and the trailers were 46 feet 31⁄2 inches (14.110 m), both being 8 feet 6 inches (2.59 m) wide at floor level and 9 feet 8 inches (2.95 m) high from rail level. There were 11 of each type, to run in four four-car formations with spares.

The accommodation was of the open saloon type, then a novelty in Britain; there were gate entrances at the end of the vehicles. The trailers seated 56 persons, and the motor coaches seated 46, with a raised section over the motor bogie.

The traction motors by Siemens were series-wound 60 hp (45 kW) gearless motors on the axles. The trains ran in a formation of four cars, the two outer vehicles being motor coaches. The motor cars were constructed to allow an early form of multiple unit operation and the front car's controller was additionally able to control the rear car's motors. The two motors at each end were connected in series at starting, then reconnected in parallel (using open circuit transition) as the train accelerated in the well established (at that time) method. This required eight cables to be run the length of the train at roof level. A further cable making nine in all linked the collector shoes at opposite ends of the four-car set to avoid problems with the large gaps in the centrally mounted conductor rail.

There was a crew of six at first: driver, driver's assistant, guard and three gatemen; the driver's assistant was subsequently eliminated. The trains used Westinghouse brakes, and the air reservoirs were charged from static compressors at Waterloo. They were charged to 100 psi (690 kPa), running down to 70 psi (480 kPa) before needing to be recharged. Lighting was run off the power circuit, with four lamps in series from the 500 V nominal.[6]

In 1937 the Southern Railway carried out a thorough review of the technical aspects of the line, now 40 years old. This led to an immediate proposal to order new rolling stock in five-car formations, in association with the provision of escalators at the City station. The scheme was delayed and the declaration of war on 3 September 1939 led to cancellation of the escalator scheme. However the rolling stock work was considered to be well advanced, and 12 motor coaches and 16 trailers were ordered from English Electric, and built at the Dick, Kerr works at Preston.

The trains were run in five-car formations, Motor coach + trailer + trailer + trailer + motor coach, with spares for overhaul. They were constructed of welded steel, and were styled in an Art Deco appearance. The motor coaches had cabs at each end, enabling single-car operation by them; they had two axle-hung traction motors rated at 190 hp (140 kW) for one hour. The new trains had on-board compressors for the air brakes, and interior lights were in two circuits, one fed from the motor car at one end of the unit, and one from the other, avoiding total lighting loss in passing conductor rail gaps. The conductor rail was altered to the outside position normal for the third-rail system. There was no train power line, and each motor coach collected its own electric supply. (This new stock was eventually classified Class 487.)

The new units were delivered through 1940, and the old cars were removed from the line on 25 October 1940, the new cars starting work on 28 October, with the line closed over the intervening weekend. The 100-pound-per-yard (50 kg/m) third rail installation had been progressive since January, with the rail put in place but not made live. New automatic signalling with trainstops was also commissioned, although Waterloo signal box was retained. The City signal box was abolished, and fully automatic working implemented there; the lay-by sidings there were abolished. The new stock did not require travelling conductors, and tickets were issued at the terminals.

When the line reopened as normal on 28 October, the City station was renamed Bank in conformity with the usage of the LPTB there.[6]

A train of 1992 stock in its original Network SouthEast livery stands at Bank station on the Waterloo & City line.

Toward the end of the 1980s the 1940 rolling stock fleet was giving increasingly difficult service. The decision was taken to acquire new vehicles as an extension to a rolling stock acquisition programme on the Central line of London Transport (LT). This required implementation of fourth rail traction current system to maintain consistency with the LT fleet: a new aluminium centre current rail was provided. (The original steel positive rail was replaced by an aluminium one in 2008.) The new vehicles had passenger operated door opening buttons, which were unlikely to be required on the Waterloo & City line.

At the same time as the rolling stock project, the construction of what became the Eurostar terminal at Waterloo main line station was being planned, requiring construction over a large area on the north side of the station, and burying the Armstrong Lift. Also, the carriages of the new rolling stock were significantly longer than those of the 1940 stock and could not be accommodated on the Armstrong Lift. Since its removal, vehicles have been craned in and out of the Waterloo depot by a mobile crane positioned near Spur Road.

On 28 May 1993 all of the old rolling stock was withdrawn, the train service being suspended temporarily. A temporary bus service was run while the old rolling stock was physically removed and the new rolling stock brought in, and the track and signalling works undertaken, with staff training. The line reopened on 19 July 1993, with a peak service frequency of 3½ minutes.

Since its introduction, this stock on the Waterloo & City has diverged significantly from that used on the Central line through various modifications, including the adoption of automatic train operation on the latter, that the two are no longer interchangeable; the Waterloo & City line continues to use train stops.

There have been proposals to extend the Waterloo & City line for nearly a century. After acquiring the Great Northern & City Railway (GN&C) in 1913 (the current Northern City Line), the Metropolitan Railway considered proposals to join the GN&C to the Waterloo & City or to the Circle line, but these never came to fruition. Any extension of the line north would be difficult because of the complex web of tube lines around Bank, and an extension south would be unlikely to provide demand that matched the cost. The narrow tunnels and short train lengths of the current route make any extension less cost-effective than larger projects such as Crossrail 2, which cost more but start with modern tunnels and promise far greater benefits.

The London Plan Working Party Report of 1949 envisaged as its Route G the electrification of the London, Tilbury & Southend Railway (LTS), and its diversion away from Fenchurch Street to Bank and on through the Waterloo & City tunnels to Waterloo and its suburban lines.[20] The Waterloo & City tunnels would have had to be bored out to main line size to enable this, at prohibitive cost. In the event only the electrification of the LTS took place, though the Docklands Light Railway tunnel from Minories to the Bank follows part of the envisaged route.

The revised Working Party Report of 1965 did not mention the Route G proposal, though it does say that "[t]he possibility of extending the Waterloo & City line northwards to Liverpool Street has been examined, but found to be physically impracticable."[21] More recently the Green Party has revived the Metropolitan's plan of connecting the Northern City and Waterloo & City lines as a Crossrail route.[22]

The line has been closed on a number of occasions for repairs and vehicle checks.
The line was shut on 1 April 2006 for refurbishment works. It re-opened on 11 September 2006, 11 days after the predicted completion date of the project. As well as the repainting and cleaning of the trains, the work included refurbishment of the tunnels, platforms and depot, and an upgrade of the track and signalling systems. During this time, the trains were also refurbished, which involved the fitting of new seat covers, a repaint of grab poles and a full exterior repaint into London Underground's corporate livery.[23] These and other works completed by 2007 were expected to boost rush-hour capacity by 25% and line capability by 12% at a cost of tens of millions of pounds. It was also claimed that the average journey will be up to 40 seconds faster.

Four new 75 hp (56 kW) battery-powered locomotives, named Walter, Lou, Anne and Kitty, were built by Clayton Equipment in Derby to haul materials and plant along the line during the closure.

Beyond these changes, Metronet had planned to refurbish Bank station by 2011,[24] but TfL's current plan now shows that the Bank refurbishment work should be complete by 2021.[25]

The same plan shows that TfL planned to install a further entrance to Bank station in Walbrook Square for completion by 2014. This was delayed, and project was finally completed in November 2018.[26][unreliable source?]

Because the Waterloo and City line is closed on Sundays, it has become a well-established and convenient location for filming, not least because when it was owned by British Rail (and its predecessors) it could be used when London Transport were unable or unwilling to allow access to their own stations or lines. The film The Long Memory contains a suicide attempt on the railway; it can be also seen in the 1962 Norman Wisdom film On the Beat; filming took place on 12 August 1961.

On 23 May 1967 scenes for a murder in the film The Liquidator were filmed at the Bank station.[6]

The remnants of one of the Greathead tunnelling shields used in the construction of the line can be seen in the interchange tunnel at Bank connecting the Waterloo and City line platforms with those of the Northern line and the Docklands Light Railway.[30] It is painted red.

The Waterloo & City line is colloquially known as The Drain.[31] The origins of this nickname seem to be uncertain; it may be due to the tunnels beneath the Thames continually leaking and the resulting water needing to be pumped out[3], or perhaps because passenger access to the platforms at Bank was by a lengthy sloping subway resembling a drain.[32]

Uniquely among London's Underground lines, virtually all infrastructure on the Waterloo & City line is completely underground, including all track, both stations, and the maintenance depot at Waterloo. (The Victoria line is also underground for the entire passenger route and all stations, but has a surface level, open-air depot for maintenance.) There are no track connections with any other railway line; all equipment transfers to and from the line are accomplished from the shaft and road crane at the Waterloo depot.

^Gillham (2001), p. 409, A plaque located at the site reads: "This Greathead Type Tunnelling Shield was left at this point 18 metres below ground level in 1898. Exposed by Edmund Nuttall Limited in 1987 during the construction of the Docklands Light Railway City Extension.".

Nigel Pennick, Waterloo and City Railway, Library of the European Tradition, Cambridge, 2000

The Engineer periodical dated 26 July 1895 and 2 August 1895 gives much more detail of the construction of the tunnels, the Greathead shield, the compressed air working and the electric locomotives, including a diagram of them. On-line versions of the periodical are available at Graces Guide [2].

Proceedings of the Institution of Civil Engineers, Volume CXXXIX, 1899 - 1900 gives an extensive description of the construction phase